The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
Free tracker included with every download this week
Can a GP Prescribe Mounjaro in the UK?
Yes, GPs can prescribe Mounjaro (tirzepatide) in the UK — but access is limited and typically happens through specialist weight management services rather than routine GP appointments. While your GP may be involved in your care, most prescriptions are issued by NHS tier 3 or tier 4 specialist weight management services following a formal assessment. Private access through online prescribing is also available without NHS referral. Understanding the different pathways can help you explore your options for accessing this prescription-only weight management injection.
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Calculate Your BMI Instantly
Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
NHS Access to Mounjaro — How It Actually Works
The NHS pathway for Mounjaro is structured in tiers:
- Tier 1–2: Your GP provides initial assessment and support through standard weight management programmes (diet, exercise, behaviour change services). Mounjaro is not typically prescribed at this stage.
- Tier 3: Specialist multidisciplinary weight management services — this is where most Mounjaro prescriptions happen. You need a GP referral to access tier 3 services. These are based in most NHS regions but have significant waiting lists (often months to years depending on your location).
- Tier 4: Specialist bariatric (weight loss surgery) services — also prescribe Mounjaro but for more severe obesity cases.
NICE (National Institute for Health and Care Excellence) has approved tirzepatide for use within NHS specialist weight management services, which means tier 3 and tier 4 services can prescribe it — but your GP cannot usually prescribe it independently. Your GP's role is typically to refer you to these services and support you during treatment.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
NHS Eligibility and Private Alternatives
To be eligible for NHS Mounjaro, you typically need a BMI of 30 kg/m² or above, or 27–29.9 with weight-related health conditions (type 2 diabetes, hypertension, cardiovascular disease, or sleep apnoea). People of South Asian, Chinese, Black African, or Black Caribbean heritage may qualify at lower BMI thresholds (27.5+) due to higher metabolic risk.
Private access is faster: You can obtain Mounjaro through a UK-licensed online prescriber without an NHS referral. A clinical assessment via online consultation determines your eligibility, and if approved, a prescription is issued and dispensed by a GPhC-registered pharmacy. This bypasses NHS waiting lists entirely but requires private payment (typically £130–£250+ per month depending on dose).
Use our free GLP-1 weight loss calculator to explore potential outcomes at different doses, and the BMI calculator to check your current eligibility based on NHS guidelines.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
Can my GP write me a Mounjaro prescription directly?
Not typically. GPs can support weight management but most cannot prescribe Mounjaro independently on the NHS. You need a referral to a specialist tier 3 weight management service, where the specialist team will assess you and prescribe if appropriate. Private GPs can prescribe following an online consultation, but this requires private payment.
What's the difference between Mounjaro prescribed by NHS and private?
NHS Mounjaro comes through specialist services with longer wait times but free prescriptions (though services vary by region). Private Mounjaro is faster (days to weeks) and doesn't require an NHS referral, but you pay out-of-pocket. The medication is identical; the difference is access pathway and cost.
How long is the NHS waiting list for Mounjaro?
Waiting times vary significantly by region (NHS Integrated Care Board). Some areas have 3–6 month waits; others exceed 18 months. Contact your local tier 3 weight management service for realistic timelines. This variability is a key reason some people choose private access.
What counts as a "weight-related health condition" for Mounjaro eligibility?
Type 2 diabetes, prediabetes, high blood pressure, abnormal cholesterol, obstructive sleep apnoea, and history of heart attack or stroke. Your GP or specialist will assess whether you have qualifying conditions alongside your BMI.
Can I switch from NHS Mounjaro to private prescription?
Yes. If your NHS waiting list is very long, you can obtain Mounjaro privately while awaiting NHS assessment. Some people continue privately; others return to NHS prescriptions once approved. Always inform both prescribers to avoid duplication or safety issues.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.